1. Field of the Invention
The present invention generally relates to apparatus for winding a wire around a toroidal core and more particularly is directed to a novel apparatus capable of automatically winding a wire around a toroidal core so as to form a toroidal coil.
2. Description of the Prior Art
When a series of work for inserting a wire into an aperture of a toroidal core and winding the wire around the toroidal core to form a toroidal coil is carried out automatically, it may be considered that a free end portion of a wire is gripped by a proper holding means, the free end portion is faced to the aperture of a toroidal core, the holding means is moved in the direction of the aperture of core so as to insert the wire into the aperture of core, the free end portion of the wire passed through the aperture of core is gripped by another holding means, the free end portion of the wire is gripped again by the former holding means, and the toroidal core is rotated by one revolution whereby to wind the wire around the toroidal core once, which series of works are repeated several times to make a toroidal coil with a desired number of windings.
However, a toroidal core used by a magnetic head of a video tape recorder, an electric calculator and the like is very small so that when a wire is wound around such toroidal core, it is necessary to insert a wire into a quite small aperture of core. In this case, the free end portion of the wire held by the holding means easily bends, bringing about a great difficulty of inserting the wire into the aperture of core automatically. For this reason, in practice, the wire must be wound around the toroidal core by manual labor.
Further, when the free end portion of the wire is accurately positioned to the aperture of core of the toroidal core, it becomes necessary that a video camera is used to pick up the free end portion of the wire and the aperture of core and that a video signal is processed to detect the position of the aperture of core and that of the free end portion of the wire. When the position is detected, there is a serious problem that what portion of the aperture of core should be recognized as the position of the aperture of core. Because, the wire is very thin and its cross section is generally circular so that the center point of the free end surface of the wire is naturally recognized as the position of the wire. On the other hand, the aperture of core has an area and its shape is simple, for example, square in the first but becomes complicated as the winding process advances, so the optimum position at which the wire is inserted into the aperture of core changes incessantly. Accordingly, if such control of the position is not carried out that the optimum position at which the wire is inserted into the aperture of core is recognized as the position of the aperture of core, an extremely small error in positioning based on the limit of accuracy of the winding apparatus or the like causes the wire to be positioned at a position displaced from the aperture of core and hence there is then some fear that the wire can not be inserted into the aperture of core or that in some case the winding apparatus does not work well. Thus, it is necessary to detect the optimum wire insertion position of the aperture of core and to recognize it as the position of the aperture of core.